Imposing tighter regulatory controls on offshore oil production is the political equivalent of opposing terrorism along the Southern California coast, whose residents love cars but hate petroleum production.

When, therefore, Assemblywoman Hannah-Beth Jackson, D-Santa Barbara, introduced legislation that would prohibit oil from being barged from offshore platforms, it was certain to be approved by the Assembly controlled by her fellow Democrats.

As Jackson presented her bill on the Assembly floor last Thursday, however, another game was afoot. Political staffers from both parties were closely monitoring how a few legislators would lean on the Jackson bill, hoping that their votes would provide fodder for 2004 campaigns. Why the operatives were paying attention to the offshore oil bill is rooted in the Legislature's never-ending game of political one-upsmanship.

During much of the 1990s, partisan control of the Legislature was never certain because the state Supreme Court, which handled redistricting after the 1990 census, maximized the number of "swing" districts that could be won by either party, depending on circumstances. The court, in other words, thought that democracy was best served by forcing lawmakers and candidates to be more responsive to voters. And, in fact, there were large swings in both parties' numbers during the decade, especially in the Assembly, which went from Democratic control to Republican control and back to Democratic control.

Because partisan control of the Assembly was always in doubt, operatives for both parties constantly ran "drills" -- offering bills, amendments and procedural motions aimed at forcing incumbents in swing districts to vote in ways that might alienate significant blocs of voters when exploited by campaign hit pieces in the next election.

When leaders of both parties agreed to a legislative redistricting plan in 2001, however, their goal was to minimize, or even eliminate, uncertainty at the polls. The scheme attempted -- largely successfully -- to fix the partisan ownership of every legislative district. Protecting legislators from the will of voters may be undemocratic, with a small "d," but politicians like it.

The scheme worked in 97 percent of last year's legislative elections. Two Assembly districts and one Senate district that had been designated for Democrats went to Republicans, and there are two or three others that had been given to Republicans but might go Democratic in future elections. But out of 120 districts, only a half-dozen or so could swing one way or the other.

One aspect of this shift in ambience to near-certainty is that the partisan plotters have fewer opportunities to run their much-cherished drills. They must concentrate on just a few swing districts, which is why the offshore oil bill votes were receiving such scrutiny. A "wrong" vote on such a visceral issue could become the basis for a campaign hit piece -- but the definition of "wrong" varies from locale to locale.

Democratic operatives had their fingers crossed that Shirley Horton, a Republican assemblywoman from San Diego County, would vote against the Jackson bill. Horton is one of two GOP women to capture Democrat-designated districts last year and she's being watched very carefully. Likewise, Republican Assemblyman Abel Maldonado of Santa Maria wants to move up to the state Senate next year -- in a district that Jackson also covets -- and voting against her bill would have hurt him in a rabidly anti-offshore oil production region.

While the Democrats kept tabs on Horton and Maldonado, Republicans were watching Democratic Assemblywomen Nicole Parra of Hanford and Barbara Matthews of Tracy, since both represent Central Valley districts that could go Republican under the right circumstances. Parra, particularly, would be at risk because her district is heavily involved in oil production.

Ultimately, all the watchers were disappointed. Horton and Matthews ducked the vote altogether, while Maldonado was the only Republican to vote for it, and Parra was one of just two Democrats (the other being Fresno's Sarah Reyes) to oppose the measure, which garnered the bare minimum 41 votes to pass.

But the game will continue as the deficit-ridden budget and dozens of other bills come up for votes.